Purpose: This study seeks to examine the difference in color change depending on the mixing ratio of acidic hair dye and hair brightness and provide baseline data on the color change of hair dye using acidic hair dye.Methods: Gray, ash blue, pink, and orange colors were used alone, mixed with gloss in transparent color in the ratio of 1:1, 1:10, and 1:20, and were applied to unbleached hair, once, twice, and three times bleached hair, respectively, and color images were taken. The L<sup>*</sup>a<sup>*</sup>b<sup>*</sup> values were measured using a spectrophotometer, and their average value was obtained.Results: It was found that when acidic hair dye was used alone, hair was less bright and more saturated. Brightness increased more when acidic hair dye was mixed with transparent shimmering gloss. Also, when dyeing with pink and orange colors, it was possible to express the desired color on once-bleached hair even with a high value of yellow color. Bright grey and ash-blue color could be expressed when the gray color was bleached three times. For the pink color, high saturation could be expressed on once-bleached hair. For orange color, it was found that various orange colors could be expressed.Conclusion: This study is meaningful in that it enhances customers’ satisfaction with hair coloring and increases the efficiency of hair dyeing service by minimizing the error between the objective color desired by the designer and the customer, and the resulting color.